The position of an electron is given by vec$(r)=5\mathrm{.}39$that$(i)-6\mathrm{.}46t^2$hat$(j)+6\mathrm{.}91$hat$(k),$ with $t$ in seconds and vec$(r)$ in meters. At $t=4\mathrm{.}69s,$ what are $($a$)$ the $x-$component, $($b$)$ the $y-$component, $($c$)$ the magnitude, and $($d$)$ the angle relative to the positive direction of the $x$ axis, of the electron's velocity vec$(v)($give the angle in the range $))?$